A decent, full length pic of a Gladiator looking a little confused! Sourced from sxc.hu.

The Process:

After cutting the Gladiator out of his background with the Pen tool, I spent quite a bit of time finding the best position and size for him in the Aviva photo so it looked like he was really there on the pitch. After finding his spot and tidying up his edges and hair with a brush & mask, I created his shadow by duplicating his layer, warping with the Transform tool and adding a Gaussian Blur then making the shadow layer slightly transparent to match the stadium roof shadow.

Next, I planted Mr Gladiator firmly on the ground by hand drawing in shadows under his feet with a soft black brush. Some more shadows next. Since I put him standing under the shadow of the stadium roof, I needed to add some roof shadows onto him directly so again, using the brush, I painted on shadows, matching the lines of the stadium shadow, then made them a bit transparent to look more natural.

Finally, I added a Photo Filter Adjustment layer, just on the Gladiator and used a sampled green color from the pitch just to match him into the color scheme a bit better.